A Pancoast tumor is a tumor of the apex of the lung. It is a type of lung cancer defined primarily by its location situated at the top end of either the right or left lung. It typically spreads to nearby tissues such as the ribs and vertebrae. Most Pancoast tumors are non-small-cell lung cancers.

The growing tumor can cause compression of many nearby structures, such as the brachiocephalic vein, subclavian artery, phrenic nerve, recurrent laryngeal nerve, vagus nerve, or, characteristically, compression of a sympathetic ganglion (the stellate ganglion), which result in various presenting symptoms, most notably a range of symptoms known as Horner's syndrome due to compression of nearby sympathetic nerves.

Pancoast tumors are named for Henry Pancoast, an American radiologist, who first described them in 1924 and 1932.

Though many advances in their treatment have been made since their initial categorization, Pancoast tumors remain difficult to treat due to low rates of possible surgical intervention, therefore prognosis is still poor.

History

The Pancoast tumor was first described by Hare in 1838 as a "tumor involving certain nerves". It was not until 1924 that the tumor was described in further detail, when Henry Pancoast, a radiologist from Philadelphia, published an article in which he reported and studied many cases of apical chest tumors that all shared the same radiographic findings and associated clinical symptoms, such as pain in the upper extremity following the distribution of the eighth cervical, first and second thoracic nerve trunks, as well as "sympathetic phenomena". Pancoast went on to publish a second article in 1932 in which a name was finally given to the tumor, "superior pulmonary sulcus tumor".

Epidemiology

The Pancoast tumor is one of the more rare forms of lung cancer, only accounting for about 3-5% of lung cancer cases, with lung cancer in general being the second most common type of cancer occurring worldwide.

Like most other lung cancers, Pancoast tumors are more often seen in men and older people, with the average age of diagnosis being between 60–70 years old.

Signs and symptoms

Aside from constitutional symptoms of cancer such as malaise, fever, weight loss and fatigue, most common initial presentation of a Pancoast tumor is that of shoulder pain and upper back pain, present in up to 96% of patients.

Typically, other presentations are due to the effects of extension of the tumor into nearby structures, such as ribs, vasculature, and nerves. The results of one of these invasions is the presentation of the Horner's syndrome, which can be seen in 15–50% of patients with severe cases when involvement of the paravertebral sympathetic chain and cervical ganglion occur. A complete Horner's syndrome consists of ipsilateral miosis (constriction of the pupils), anhidrosis (lack of sweating), ptosis (drooping of the eyelid), and pseudo enophthalmos (as a result of the ptosis). In progressive cases, the brachial plexus is also affected, causing pain and weakness in the muscles of the arm and hand with a symptomatology typical of thoracic outlet syndrome. The tumor can also compress the recurrent laryngeal nerve and from this a hoarse voice and "bovine" (non-explosive) cough may occur.

  • Exposure to harmful chemicals (radon gas, asbestos, and heavy metals)

Diagnosis

Diagnosis of a Pancoast tumor can be difficult in the early stages due to the similarity of its symptoms with other conditions such as arthritis, with shoulder pain being one of the only symptoms that might indicate further imaging for a patient. Though a chest x-ray is a good screening test and might be the first mode of imaging used, they are not easily seen during the early stages of the disease due to their size and location in the chest.

Following the initial imaging, a CT scan or MRI is preferred since both can provide more details and information such as size, lymph node involvement and other areas of invasion, such as vascular involvement.

It is important to consider other possible causes with similar physical presentation to the Pancoast tumor. Such conditions to consider as part of a differential diagnosis include:

  • Lymphoma
  • Hemangiopericytoma
  • Adenoid Cystic Carcinoma
  • Plasmacytoma
  • Mesothelioma
  • Pulmonary metastatic malignancies, particularly from the cervix, larynx, liver, bladder, and thyroid gland